/*
 * Copyright 2002-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.bc.commoncore.util;

import java.io.ByteArrayOutputStream;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TimeZone;
import java.util.TreeSet;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Miscellaneous {@link String} utility methods.
 * <p>
 * <p>
 * Mainly for internal use within the framework; consider
 * <a href="http://jakarta.apache.org/commons/lang/">Jakarta's Commons Lang</a>
 * for a more comprehensive suite of String utilities.
 * <p>
 * <p>
 * This class delivers some simple functionality that should really be provided
 * by the core Java {@code String} and {@link StringBuilder} classes, such as
 * the ability to {@link #replace} all occurrences of a given substring in a
 * target string. It also provides easy-to-use methods to convert between
 * delimited strings, such as CSV strings, and collections and arrays.
 */
public abstract class StringUtils {

    private static final String FOLDER_SEPARATOR = "/";

    private static final String WINDOWS_FOLDER_SEPARATOR = "\\";

    private static final String TOP_PATH = "..";

    private static final String CURRENT_PATH = ".";

    private static final char EXTENSION_SEPARATOR = '.';

    public static final String EMPTY = "";

    // ---------------------------------------------------------------------
    // General convenience methods for working with Strings
    // ---------------------------------------------------------------------

    /**
     * Check whether the given String is empty.
     * <p>
     * This method accepts any Object as an argument, comparing it to
     * {@code null} and the empty String. As a consequence, this method will
     * never return {@code true} for a non-null non-String object.
     * <p>
     * The Object signature is useful for general attribute handling code that
     * commonly deals with Strings but generally has to iterate over Objects
     * since attributes may e.g. be primitive value objects as well.
     *
     * @param str the candidate String
     * @since 3.2.1
     */
    public static boolean isEmpty(String str) {
        return (str == null || "".equals(str));
    }

    /**
     * Check that the given CharSequence is neither {@code null} nor of length
     * 0. Note: Will return {@code true} for a CharSequence that purely consists
     * of whitespace.
     * <p>
     * <p>
     * <pre class="code">
     * StringUtils.hasLength(null) = false
     * StringUtils.hasLength("") = false
     * StringUtils.hasLength(" ") = true
     * StringUtils.hasLength("Hello") = true
     * </pre>
     *
     * @param str the CharSequence to check (may be {@code null})
     * @return {@code true} if the CharSequence is not null and has length
     * @see #hasText(String)
     */
    public static boolean hasLength(CharSequence str) {
        return (str != null && str.length() > 0);
    }

    /**
     * Check that the given String is neither {@code null} nor of length 0.
     * Note: Will return {@code true} for a String that purely consists of
     * whitespace.
     *
     * @param str the String to check (may be {@code null})
     * @return {@code true} if the String is not null and has length
     * @see #hasLength(CharSequence)
     */
    public static boolean hasLength(String str) {
        return hasLength((CharSequence) str);
    }

    public static String trim(String str) {
        return str == null ? "" : str.trim();
    }

    /**
     * Check whether the given CharSequence has actual text. More specifically,
     * returns {@code true} if the string not {@code null}, its length is
     * greater than 0, and it contains at least one non-whitespace character.
     * <p>
     * <p>
     * <pre class="code">
     * StringUtils.hasText(null) = false
     * StringUtils.hasText("") = false
     * StringUtils.hasText(" ") = false
     * StringUtils.hasText("12345") = true
     * StringUtils.hasText(" 12345 ") = true
     * </pre>
     *
     * @param str the CharSequence to check (may be {@code null})
     * @return {@code true} if the CharSequence is not {@code null}, its length
     * is greater than 0, and it does not contain whitespace only
     * @see Character#isWhitespace
     */
    public static boolean hasText(CharSequence str) {
        if (!hasLength(str)) {
            return false;
        }
        int strLen = str.length();
        for (int i = 0; i < strLen; i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                return true;
            }
        }
        return false;
    }

    /**
     * Check whether the given String has actual text. More specifically,
     * returns {@code true} if the string not {@code null}, its length is
     * greater than 0, and it contains at least one non-whitespace character.
     *
     * @param str the String to check (may be {@code null})
     * @return {@code true} if the String is not {@code null}, its length is
     * greater than 0, and it does not contain whitespace only
     * @see #hasText(CharSequence)
     */
    public static boolean hasText(String str) {
        return hasText((CharSequence) str);
    }

    /**
     * Check whether the given CharSequence contains any whitespace characters.
     *
     * @param str the CharSequence to check (may be {@code null})
     * @return {@code true} if the CharSequence is not empty and contains at
     * least 1 whitespace character
     * @see Character#isWhitespace
     */
    public static boolean containsWhitespace(CharSequence str) {
        if (!hasLength(str)) {
            return false;
        }
        int strLen = str.length();
        for (int i = 0; i < strLen; i++) {
            if (Character.isWhitespace(str.charAt(i))) {
                return true;
            }
        }
        return false;
    }

    /**
     * Check whether the given String contains any whitespace characters.
     *
     * @param str the String to check (may be {@code null})
     * @return {@code true} if the String is not empty and contains at least 1
     * whitespace character
     * @see #containsWhitespace(CharSequence)
     */
    public static boolean containsWhitespace(String str) {
        return containsWhitespace((CharSequence) str);
    }

    /**
     * Trim leading and trailing whitespace from the given String.
     *
     * @param str the String to check
     * @return the trimmed String
     * @see java.lang.Character#isWhitespace
     */
    public static String trimWhitespace(String str) {
        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) {
            sb.deleteCharAt(0);
        }
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) {
            sb.deleteCharAt(sb.length() - 1);
        }
        return sb.toString();
    }

    /**
     * Trim <i>all</i> whitespace from the given String: leading, trailing, and
     * in between characters.
     *
     * @param str the String to check
     * @return the trimmed String
     * @see java.lang.Character#isWhitespace
     */
    public static String trimAllWhitespace(String str) {
        if (!hasLength(str)) {
            return str;
        }
        int len = str.length();
        StringBuilder sb = new StringBuilder(str.length());
        for (int i = 0; i < len; i++) {
            char c = str.charAt(i);
            if (!Character.isWhitespace(c)) {
                sb.append(c);
            }
        }
        return sb.toString();
    }

    /**
     * Trim leading whitespace from the given String.
     *
     * @param str the String to check
     * @return the trimmed String
     * @see java.lang.Character#isWhitespace
     */
    public static String trimLeadingWhitespace(String str) {
        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) {
            sb.deleteCharAt(0);
        }
        return sb.toString();
    }

    /**
     * Trim trailing whitespace from the given String.
     *
     * @param str the String to check
     * @return the trimmed String
     * @see java.lang.Character#isWhitespace
     */
    public static String trimTrailingWhitespace(String str) {
        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) {
            sb.deleteCharAt(sb.length() - 1);
        }
        return sb.toString();
    }

    /**
     * Trim all occurrences of the supplied leading character from the given
     * String.
     *
     * @param str              the String to check
     * @param leadingCharacter the leading character to be trimmed
     * @return the trimmed String
     */
    public static String trimLeadingCharacter(String str, char leadingCharacter) {
        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && sb.charAt(0) == leadingCharacter) {
            sb.deleteCharAt(0);
        }
        return sb.toString();
    }

    /**
     * Trim all occurrences of the supplied trailing character from the given
     * String.
     *
     * @param str               the String to check
     * @param trailingCharacter the trailing character to be trimmed
     * @return the trimmed String
     */
    public static String trimTrailingCharacter(String str, char trailingCharacter) {
        if (!hasLength(str)) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str);
        while (sb.length() > 0 && sb.charAt(sb.length() - 1) == trailingCharacter) {
            sb.deleteCharAt(sb.length() - 1);
        }
        return sb.toString();
    }

    /**
     * Test if the given String starts with the specified prefix, ignoring
     * upper/lower case.
     *
     * @param str    the String to check
     * @param prefix the prefix to look for
     * @see java.lang.String#startsWith
     */
    public static boolean startsWithIgnoreCase(String str, String prefix) {
        if (str == null || prefix == null) {
            return false;
        }
        if (str.startsWith(prefix)) {
            return true;
        }
        if (str.length() < prefix.length()) {
            return false;
        }
        String lcStr = str.substring(0, prefix.length()).toLowerCase();
        String lcPrefix = prefix.toLowerCase();
        return lcStr.equals(lcPrefix);
    }

    /**
     * Test if the given String ends with the specified suffix, ignoring
     * upper/lower case.
     *
     * @param str    the String to check
     * @param suffix the suffix to look for
     * @see java.lang.String#endsWith
     */
    public static boolean endsWithIgnoreCase(String str, String suffix) {
        if (str == null || suffix == null) {
            return false;
        }
        if (str.endsWith(suffix)) {
            return true;
        }
        if (str.length() < suffix.length()) {
            return false;
        }

        String lcStr = str.substring(str.length() - suffix.length()).toLowerCase();
        String lcSuffix = suffix.toLowerCase();
        return lcStr.equals(lcSuffix);
    }

    /**
     * Test whether the given string matches the given substring at the given
     * index.
     *
     * @param str       the original string (or StringBuilder)
     * @param index     the index in the original string to start matching against
     * @param substring the substring to match at the given index
     */
    public static boolean substringMatch(CharSequence str, int index, CharSequence substring) {
        for (int j = 0; j < substring.length(); j++) {
            int i = index + j;
            if (i >= str.length() || str.charAt(i) != substring.charAt(j)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Count the occurrences of the substring in string s.
     *
     * @param str string to search in. Return 0 if this is null.
     * @param sub string to search for. Return 0 if this is null.
     */
    public static int countOccurrencesOf(String str, String sub) {
        if (str == null || sub == null || str.length() == 0 || sub.length() == 0) {
            return 0;
        }
        int count = 0;
        int pos = 0;
        int idx;
        while ((idx = str.indexOf(sub, pos)) != -1) {
            ++count;
            pos = idx + sub.length();
        }
        return count;
    }

    /**
     * Replace all occurrences of a substring within a string with another
     * string.
     *
     * @param inString   String to examine
     * @param oldPattern String to replace
     * @param newPattern String to insert
     * @return a String with the replacements
     */
    public static String replace(String inString, String oldPattern, String newPattern) {
        if (!hasLength(inString) || !hasLength(oldPattern) || newPattern == null) {
            return inString;
        }
        StringBuilder sb = new StringBuilder();
        int pos = 0; // our position in the old string
        int index = inString.indexOf(oldPattern);
        // the index of an occurrence we've found, or -1
        int patLen = oldPattern.length();
        while (index >= 0) {
            sb.append(inString.substring(pos, index));
            sb.append(newPattern);
            pos = index + patLen;
            index = inString.indexOf(oldPattern, pos);
        }
        sb.append(inString.substring(pos));
        // remember to append any characters to the right of a match
        return sb.toString();
    }

    /**
     * Delete all occurrences of the given substring.
     *
     * @param inString the original String
     * @param pattern  the pattern to delete all occurrences of
     * @return the resulting String
     */
    public static String delete(String inString, String pattern) {
        return replace(inString, pattern, "");
    }

    /**
     * Delete any character in a given String.
     *
     * @param inString      the original String
     * @param charsToDelete a set of characters to delete. E.g. "az\n" will delete 'a's,
     *                      'z's and new lines.
     * @return the resulting String
     */
    public static String deleteAny(String inString, String charsToDelete) {
        if (!hasLength(inString) || !hasLength(charsToDelete)) {
            return inString;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < inString.length(); i++) {
            char c = inString.charAt(i);
            if (charsToDelete.indexOf(c) == -1) {
                sb.append(c);
            }
        }
        return sb.toString();
    }

    // ---------------------------------------------------------------------
    // Convenience methods for working with formatted Strings
    // ---------------------------------------------------------------------

    /**
     * Quote the given String with single quotes.
     *
     * @param str the input String (e.g. "myString")
     * @return the quoted String (e.g. "'myString'"), or {@code null} if the
     * input was {@code null}
     */
    public static String quote(String str) {
        return (str != null ? "'" + str + "'" : null);
    }

    /**
     * Turn the given Object into a String with single quotes if it is a String;
     * keeping the Object as-is else.
     *
     * @param obj the input Object (e.g. "myString")
     * @return the quoted String (e.g. "'myString'"), or the input object as-is
     * if not a String
     */
    public static Object quoteIfString(Object obj) {
        return (obj instanceof String ? quote((String) obj) : obj);
    }

    /**
     * Unqualify a string qualified by a '.' dot character. For example,
     * "this.name.is.qualified", returns "qualified".
     *
     * @param qualifiedName the qualified name
     */
    public static String unqualify(String qualifiedName) {
        return unqualify(qualifiedName, '.');
    }

    /**
     * Unqualify a string qualified by a separator character. For example,
     * "this:name:is:qualified" returns "qualified" if using a ':' separator.
     *
     * @param qualifiedName the qualified name
     * @param separator     the separator
     */
    public static String unqualify(String qualifiedName, char separator) {
        return qualifiedName.substring(qualifiedName.lastIndexOf(separator) + 1);
    }

    /**
     * Capitalize a {@code String}, changing the first letter to upper case as
     * per {@link Character#toUpperCase(char)}. No other letters are changed.
     *
     * @param str the String to capitalize, may be {@code null}
     * @return the capitalized String, {@code null} if null
     */
    public static String capitalize(String str) {
        return changeFirstCharacterCase(str, true);
    }

    /**
     * Uncapitalize a {@code String}, changing the first letter to lower case as
     * per {@link Character#toLowerCase(char)}. No other letters are changed.
     *
     * @param str the String to uncapitalize, may be {@code null}
     * @return the uncapitalized String, {@code null} if null
     */
    public static String uncapitalize(String str) {
        return changeFirstCharacterCase(str, false);
    }

    private static String changeFirstCharacterCase(String str, boolean capitalize) {
        if (str == null || str.length() == 0) {
            return str;
        }
        StringBuilder sb = new StringBuilder(str.length());
        if (capitalize) {
            sb.append(Character.toUpperCase(str.charAt(0)));
        } else {
            sb.append(Character.toLowerCase(str.charAt(0)));
        }
        sb.append(str.substring(1));
        return sb.toString();
    }

    /**
     * Extract the filename from the given path, e.g. "mypath/myfile.txt" ->
     * "myfile.txt".
     *
     * @param path the file path (may be {@code null})
     * @return the extracted filename, or {@code null} if none
     */
    public static String getFilename(String path) {
        if (path == null) {
            return null;
        }
        int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        return (separatorIndex != -1 ? path.substring(separatorIndex + 1) : path);
    }

    /**
     * Extract the filename extension from the given path, e.g.
     * "mypath/myfile.txt" -> "txt".
     *
     * @param path the file path (may be {@code null})
     * @return the extracted filename extension, or {@code null} if none
     */
    public static String getFilenameExtension(String path) {
        if (path == null) {
            return null;
        }
        int extIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
        if (extIndex == -1) {
            return null;
        }
        int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        if (folderIndex > extIndex) {
            return null;
        }
        return path.substring(extIndex + 1);
    }

    /**
     * Strip the filename extension from the given path, e.g.
     * "mypath/myfile.txt" -> "mypath/myfile".
     *
     * @param path the file path (may be {@code null})
     * @return the path with stripped filename extension, or {@code null} if
     * none
     */
    public static String stripFilenameExtension(String path) {
        if (path == null) {
            return null;
        }
        int extIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
        if (extIndex == -1) {
            return path;
        }
        int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        if (folderIndex > extIndex) {
            return path;
        }
        return path.substring(0, extIndex);
    }

    /**
     * Apply the given relative path to the given path, assuming standard Java
     * folder separation (i.e. "/" separators).
     *
     * @param path         the path to start from (usually a full file path)
     * @param relativePath the relative path to apply (relative to the full file path
     *                     above)
     * @return the full file path that results from applying the relative path
     */
    public static String applyRelativePath(String path, String relativePath) {
        int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
        if (separatorIndex != -1) {
            String newPath = path.substring(0, separatorIndex);
            if (!relativePath.startsWith(FOLDER_SEPARATOR)) {
                newPath += FOLDER_SEPARATOR;
            }
            return newPath + relativePath;
        } else {
            return relativePath;
        }
    }

    /**
     * Normalize the path by suppressing sequences like "path/.." and inner
     * simple dots.
     * <p>
     * The result is convenient for path comparison. For other uses, notice that
     * Windows separators ("\") are replaced by simple slashes.
     *
     * @param path
     *            the original path
     * @return the normalized path
     */
    /*
     * public static String cleanPath(String path) { if (path == null) { return
     * null; } String pathToUse = replace(path, WINDOWS_FOLDER_SEPARATOR,
     * FOLDER_SEPARATOR);
     *
     * // Strip prefix from path to analyze, to not treat it as part of the //
     * first path element. This is necessary to correctly parse paths like //
     * "file:core/../core/io/Resource.class", where the ".." should just //
     * strip the first "core" directory while keeping the "file:" prefix. int
     * prefixIndex = pathToUse.indexOf(":"); String prefix = ""; if (prefixIndex
     * != -1) { prefix = pathToUse.substring(0, prefixIndex + 1); if
     * (prefix.contains("/")) { prefix = ""; } else { pathToUse =
     * pathToUse.substring(prefixIndex + 1); } } if
     * (pathToUse.startsWith(FOLDER_SEPARATOR)) { prefix = prefix +
     * FOLDER_SEPARATOR; pathToUse = pathToUse.substring(1); }
     *
     * String[] pathArray = delimitedListToStringArray(pathToUse,
     * FOLDER_SEPARATOR); List<String> pathElements = new LinkedList<String>();
     * int tops = 0;
     *
     * for (int i = pathArray.length - 1; i >= 0; i--) { String element =
     * pathArray[i]; if (CURRENT_PATH.equals(element)) { // Points to current
     * directory - drop it. } else if (TOP_PATH.equals(element)) { //
     * Registering top path found. tops++; } else { if (tops > 0) { // Merging
     * path element with element corresponding to top path. tops--; } else { //
     * Normal path element found. pathElements.add(0, element); } } }
     *
     * // Remaining top paths need to be retained. for (int i = 0; i < tops;
     * i++) { pathElements.add(0, TOP_PATH); }
     *
     * return prefix + collectionToDelimitedString(pathElements,
     * FOLDER_SEPARATOR); }
     */

    /**
     * Compare two paths after normalization of them.
     *
     * @param path1
     *            first path for comparison
     * @param path2
     *            second path for comparison
     * @return whether the two paths are equivalent after normalization
     */
    /*
     * public static boolean pathEquals(String path1, String path2) { return
     * cleanPath(path1).equals(cleanPath(path2)); }
     */

    /**
     * Parse the given {@code localeString} value into a {@link Locale}.
     * <p>
     * This is the inverse operation of {@link Locale#toString Locale's
     * toString}.
     *
     * @param localeString the locale String, following {@code Locale's}
     *                     {@code toString()} format ("en", "en_UK", etc); also accepts
     *                     spaces as separators, as an alternative to underscores
     * @return a corresponding {@code Locale} instance
     * @throws IllegalArgumentException in case of an invalid locale specification
     */
    public static Locale parseLocaleString(String localeString) {
        if (org.apache.commons.lang.StringUtils.isBlank(localeString)) {
            return null;
        }
        String[] parts = tokenizeToStringArray(localeString, "_ ", false, false);
        if (parts == null) {
            return null;
        }
        String language = (parts.length > 0 ? parts[0] : "");
        String country = (parts.length > 1 ? parts[1] : "");
        validateLocalePart(language);
        validateLocalePart(country);
        String variant = "";
        if (parts.length > 2) {
            // There is definitely a variant, and it is everything after the
            // country
            // code sans the separator between the country code and the variant.
            int endIndexOfCountryCode = localeString.indexOf(country, language.length()) + country.length();
            // Strip off any leading '_' and whitespace, what's left is the
            // variant.
            variant = trimLeadingWhitespace(localeString.substring(endIndexOfCountryCode));
            if (org.apache.commons.lang.StringUtils.isNotBlank(variant) && variant.startsWith("_")) {
                variant = trimLeadingCharacter(variant, '_');
            }
        }
        return (language.length() > 0 ? new Locale(language, country, variant) : null);
    }

    private static void validateLocalePart(String localePart) {
        for (int i = 0; i < localePart.length(); i++) {
            char ch = localePart.charAt(i);
            if (ch != '_' && ch != ' ' && !Character.isLetterOrDigit(ch)) {
                throw new IllegalArgumentException("Locale part \"" + localePart + "\" contains invalid characters");
            }
        }
    }

    /**
     * Determine the RFC 3066 compliant language tag, as used for the HTTP
     * "Accept-Language" header.
     *
     * @param locale the Locale to transform to a language tag
     * @return the RFC 3066 compliant language tag as String
     */
    public static String toLanguageTag(Locale locale) {
        return locale.getLanguage() + (hasText(locale.getCountry()) ? "-" + locale.getCountry() : "");
    }

    /**
     * Parse the given {@code timeZoneString} value into a {@link TimeZone}.
     *
     * @param timeZoneString the time zone String, following
     *                       {@link TimeZone#getTimeZone(String)} but throwing
     *                       {@link IllegalArgumentException} in case of an invalid time
     *                       zone specification
     * @return a corresponding {@link TimeZone} instance
     * @throws IllegalArgumentException in case of an invalid time zone specification
     */
    public static TimeZone parseTimeZoneString(String timeZoneString) {
        TimeZone timeZone = TimeZone.getTimeZone(timeZoneString);
        if ("GMT".equals(timeZone.getID()) && !timeZoneString.startsWith("GMT")) {
            // We don't want that GMT fallback...
            throw new IllegalArgumentException("Invalid time zone specification '" + timeZoneString + "'");
        }
        return timeZone;
    }

    // ---------------------------------------------------------------------
    // Convenience methods for working with String arrays
    // ---------------------------------------------------------------------

    /**
     * Append the given String to the given String array, returning a new array
     * consisting of the input array contents plus the given String.
     *
     * @param array
     *            the array to append to (can be {@code null})
     * @param str
     *            the String to append
     * @return the new array (never {@code null})
     */
    /*
     * public static String[] addStringToArray(String[] array, String str) { if
     * (ObjectUtils.isEmpty(array)) { return new String[] {str}; } String[]
     * newArr = new String[array.length + 1]; System.arraycopy(array, 0, newArr,
     * 0, array.length); newArr[array.length] = str; return newArr; }
     */

    /**
     * Concatenate the given String arrays into one, with overlapping array
     * elements included twice.
     * <p>
     * The Order of elements in the original arrays is preserved.
     *
     * @param array1
     *            the first array (can be {@code null})
     * @param array2
     *            the second array (can be {@code null})
     * @return the new array ({@code null} if both given arrays were
     *         {@code null})
     */
    /*
     * public static String[] concatenateStringArrays(String[] array1, String[]
     * array2) { if (ObjectUtils.isEmpty(array1)) { return array2; } if
     * (ObjectUtils.isEmpty(array2)) { return array1; } String[] newArr = new
     * String[array1.length + array2.length]; System.arraycopy(array1, 0,
     * newArr, 0, array1.length); System.arraycopy(array2, 0, newArr,
     * array1.length, array2.length); return newArr; }
     */

    /**
     * Merge the given String arrays into one, with overlapping array elements
     * only included once.
     * <p>
     * The Order of elements in the original arrays is preserved (with the
     * exception of overlapping elements, which are only included on their first
     * occurrence).
     *
     * @param array1
     *            the first array (can be {@code null})
     * @param array2
     *            the second array (can be {@code null})
     * @return the new array ({@code null} if both given arrays were
     *         {@code null})
     */
    /*
     * public static String[] mergeStringArrays(String[] array1, String[]
     * array2) { if (ObjectUtils.isEmpty(array1)) { return array2; } if
     * (ObjectUtils.isEmpty(array2)) { return array1; } List<String> result =
     * new ArrayList<String>(); result.addAll(Arrays.asList(array1)); for
     * (String str : array2) { if (!result.contains(str)) { result.add(str); } }
     * return toStringArray(result); }
     */

    /**
     * Turn given source String array into sorted array.
     *
     * @param array
     *            the source array
     * @return the sorted array (never {@code null})
     */
    /*
     * public static String[] sortStringArray(String[] array) { if
     * (ObjectUtils.isEmpty(array)) { return new String[0]; }
     * Arrays.sort(array); return array; }
     */

    /**
     * Copy the given Collection into a String array. The Collection must
     * contain String elements only.
     *
     * @param collection the Collection to copy
     * @return the String array ({@code null} if the passed-in Collection was
     * {@code null})
     */
    public static String[] toStringArray(Collection<String> collection) {
        if (collection == null) {
            return null;
        }
        return collection.toArray(new String[collection.size()]);
    }

    /**
     * Copy the given Enumeration into a String array. The Enumeration must
     * contain String elements only.
     *
     * @param enumeration the Enumeration to copy
     * @return the String array ({@code null} if the passed-in Enumeration was
     * {@code null})
     */
    public static String[] toStringArray(Enumeration<String> enumeration) {
        if (enumeration == null) {
            return null;
        }
        List<String> list = Collections.list(enumeration);
        return list.toArray(new String[list.size()]);
    }

    /**
     * Trim the elements of the given String array, calling
     * {@code String.trim()} on each of them.
     *
     * @param array
     *            the original String array
     * @return the resulting array (of the same size) with trimmed elements
     */
    /*
     * public static String[] trimArrayElements(String[] array) { if
     * (ObjectUtils.isEmpty(array)) { return new String[0]; } String[] result =
     * new String[array.length]; for (int i = 0; i < array.length; i++) { String
     * element = array[i]; result[i] = (element != null ? element.trim() :
     * null); } return result; }
     */

    /**
     * Remove duplicate Strings from the given array. Also sorts the array, as
     * it uses a TreeSet.
     *
     * @param array
     *            the String array
     * @return an array without duplicates, in natural sort Order
     */
    /*
     * public static String[] removeDuplicateStrings(String[] array) { if
     * (ObjectUtils.isEmpty(array)) { return array; } Set<String> set = new
     * TreeSet<String>(); for (String element : array) { set.add(element); }
     * return toStringArray(set); }
     */

    /**
     * Split a String at the first occurrence of the delimiter. Does not include
     * the delimiter in the result.
     *
     * @param toSplit   the string to split
     * @param delimiter to split the string up with
     * @return a two element array with index 0 being before the delimiter, and
     * index 1 being after the delimiter (neither element includes the
     * delimiter); or {@code null} if the delimiter wasn't found in the
     * given input String
     */
    public static String[] split(String toSplit, String delimiter) {
        if (!hasLength(toSplit) || !hasLength(delimiter)) {
            return null;
        }
        int offset = toSplit.indexOf(delimiter);
        if (offset < 0) {
            return null;
        }
        String beforeDelimiter = toSplit.substring(0, offset);
        String afterDelimiter = toSplit.substring(offset + delimiter.length());
        return new String[]{beforeDelimiter, afterDelimiter};
    }

    /**
     * Take an array Strings and split each element based on the given
     * delimiter. A {@code Properties} instance is then generated, with the left
     * of the delimiter providing the key, and the right of the delimiter
     * providing the value.
     * <p>
     * Will trim both the key and value before adding them to the
     * {@code Properties} instance.
     *
     * @param array
     *            the array to process
     * @param delimiter
     *            to split each element using (typically the equals symbol)
     * @return a {@code Properties} instance representing the array contents, or
     *         {@code null} if the array to process was null or empty
     */
    /*
     * public static Properties splitArrayElementsIntoProperties(String[] array,
     * String delimiter) { return splitArrayElementsIntoProperties(array,
     * delimiter, null); }
     */

    /**
     * Take an array Strings and split each element based on the given
     * delimiter. A {@code Properties} instance is then generated, with the left
     * of the delimiter providing the key, and the right of the delimiter
     * providing the value.
     * <p>
     * Will trim both the key and value before adding them to the
     * {@code Properties} instance.
     *
     * @param array
     *            the array to process
     * @param delimiter
     *            to split each element using (typically the equals symbol)
     * @param charsToDelete
     *            one or more characters to remove from each element prior to
     *            attempting the split operation (typically the quotation mark
     *            symbol), or {@code null} if no removal should occur
     * @return a {@code Properties} instance representing the array contents, or
     *         {@code null} if the array to process was {@code null} or empty
     */
    /*
     * public static Properties splitArrayElementsIntoProperties( String[]
     * array, String delimiter, String charsToDelete) {
     *
     * if (ObjectUtils.isEmpty(array)) { return null; } Properties result = new
     * Properties(); for (String element : array) { if (charsToDelete != null) {
     * element = deleteAny(element, charsToDelete); } String[] splittedElement =
     * split(element, delimiter); if (splittedElement == null) { continue; }
     * result.setProperty(splittedElement[0].trim(), splittedElement[1].trim());
     * } return result; }
     */

    /**
     * Tokenize the given String into a String array via a StringTokenizer.
     * Trims tokens and omits empty tokens.
     * <p>
     * The given delimiters string is supposed to consist of any number of
     * delimiter characters. Each of those characters can be used to separate
     * tokens. A delimiter is always a single character; for multi-character
     * delimiters, consider using {@code delimitedListToStringArray}
     *
     * @param str        the String to tokenize
     * @param delimiters the delimiter characters, assembled as String (each of those
     *                   characters is individually considered as delimiter).
     * @return an array of the tokens
     * @see java.util.StringTokenizer
     * @see String#trim()
     * @see #delimitedListToStringArray
     */
    public static String[] tokenizeToStringArray(String str, String delimiters) {
        return tokenizeToStringArray(str, delimiters, true, true);
    }

    /**
     * Tokenize the given String into a String array via a StringTokenizer.
     * <p>
     * The given delimiters string is supposed to consist of any number of
     * delimiter characters. Each of those characters can be used to separate
     * tokens. A delimiter is always a single character; for multi-character
     * delimiters, consider using {@code delimitedListToStringArray}
     *
     * @param str               the String to tokenize
     * @param delimiters        the delimiter characters, assembled as String (each of those
     *                          characters is individually considered as delimiter)
     * @param trimTokens        trim the tokens via String's {@code trim}
     * @param ignoreEmptyTokens omit empty tokens from the result array (only applies to
     *                          tokens that are empty after trimming; StringTokenizer will not
     *                          consider subsequent delimiters as token in the first place).
     * @return an array of the tokens ({@code null} if the input String was
     * {@code null})
     * @see java.util.StringTokenizer
     * @see String#trim()
     * @see #delimitedListToStringArray
     */
    public static String[] tokenizeToStringArray(String str, String delimiters, boolean trimTokens,
                                                 boolean ignoreEmptyTokens) {

        if (str == null) {
            return null;
        }
        StringTokenizer st = new StringTokenizer(str, delimiters);
        List<String> tokens = new ArrayList<String>();
        while (st.hasMoreTokens()) {
            String token = st.nextToken();
            if (trimTokens) {
                token = token.trim();
            }
            if (!ignoreEmptyTokens || token.length() > 0) {
                tokens.add(token);
            }
        }
        return toStringArray(tokens);
    }

    /**
     * Take a String which is a delimited list and convert it to a String array.
     * <p>
     * A single delimiter can consists of more than one character: It will still
     * be considered as single delimiter string, rather than as bunch of
     * potential delimiter characters - in contrast to
     * {@code tokenizeToStringArray}.
     *
     * @param str       the input String
     * @param delimiter the delimiter between elements (this is a single delimiter,
     *                  rather than a bunch individual delimiter characters)
     * @return an array of the tokens in the list
     * @see #tokenizeToStringArray
     */
    public static String[] delimitedListToStringArray(String str, String delimiter) {
        return delimitedListToStringArray(str, delimiter, null);
    }

    /**
     * Take a String which is a delimited list and convert it to a String array.
     * <p>
     * A single delimiter can consists of more than one character: It will still
     * be considered as single delimiter string, rather than as bunch of
     * potential delimiter characters - in contrast to
     * {@code tokenizeToStringArray}.
     *
     * @param str           the input String
     * @param delimiter     the delimiter between elements (this is a single delimiter,
     *                      rather than a bunch individual delimiter characters)
     * @param charsToDelete a set of characters to delete. Useful for deleting unwanted
     *                      line breaks: e.g. "\r\n\f" will delete all new lines and line
     *                      feeds in a String.
     * @return an array of the tokens in the list
     * @see #tokenizeToStringArray
     */
    public static String[] delimitedListToStringArray(String str, String delimiter, String charsToDelete) {
        if (str == null) {
            return new String[0];
        }
        if (delimiter == null) {
            return new String[]{str};
        }
        List<String> result = new ArrayList<String>();
        if ("".equals(delimiter)) {
            for (int i = 0; i < str.length(); i++) {
                result.add(deleteAny(str.substring(i, i + 1), charsToDelete));
            }
        } else {
            int pos = 0;
            int delPos;
            while ((delPos = str.indexOf(delimiter, pos)) != -1) {
                result.add(deleteAny(str.substring(pos, delPos), charsToDelete));
                pos = delPos + delimiter.length();
            }
            if (str.length() > 0 && pos <= str.length()) {
                // Add rest of String, but not in case of empty input.
                result.add(deleteAny(str.substring(pos), charsToDelete));
            }
        }
        return toStringArray(result);
    }

    /**
     * Convert a CSV list into an array of Strings.
     *
     * @param str the input String
     * @return an array of Strings, or the empty array in case of empty input
     */
    public static String[] commaDelimitedListToStringArray(String str) {
        return delimitedListToStringArray(str, ",");
    }

    /**
     * Convenience method to convert a CSV string list to a set. Note that this
     * will suppress duplicates.
     *
     * @param str the input String
     * @return a Set of String entries in the list
     */
    public static Set<String> commaDelimitedListToSet(String str) {
        Set<String> set = new TreeSet<String>();
        String[] tokens = commaDelimitedListToStringArray(str);
        for (String token : tokens) {
            set.add(token);
        }
        return set;
    }

    /**
     * Convenience method to return a Collection as a delimited (e.g. CSV)
     * String. E.g. useful for {@code toString()} implementations.
     *
     * @param coll   the Collection to display
     * @param delim  the delimiter to use (probably a ",")
     * @param prefix the String to start each element with
     * @param suffix the String to end each element with
     * @return the delimited String
     */
    public static String collectionToDelimitedString(Collection<?> coll, String delim, String prefix, String suffix) {
        if (CollectionUtils.isEmpty(coll)) {
            return "";
        }
        StringBuilder sb = new StringBuilder();
        Iterator<?> it = coll.iterator();
        while (it.hasNext()) {
            sb.append(prefix).append(it.next()).append(suffix);
            if (it.hasNext()) {
                sb.append(delim);
            }
        }
        return sb.toString();
    }

    /**
     * Convenience method to return a Collection as a delimited (e.g. CSV)
     * String. E.g. useful for {@code toString()} implementations.
     *
     * @param coll  the Collection to display
     * @param delim the delimiter to use (probably a ",")
     * @return the delimited String
     */
    public static String collectionToDelimitedString(Collection<?> coll, String delim) {
        return collectionToDelimitedString(coll, delim, "", "");
    }

    /**
     * Convenience method to return a Collection as a CSV String. E.g. useful
     * for {@code toString()} implementations.
     *
     * @param coll
     *            the Collection to display
     * @return the delimited String
     */
    /*
     * public static String collectionToCommaDelimitedString(Collection<?> coll)
     * { return collectionToDelimitedString(coll, ","); }
     */

    /**
     * Convenience method to return a String array as a delimited (e.g. CSV)
     * String. E.g. useful for {@code toString()} implementations.
     *
     * @param arr   the array to display
     * @param delim the delimiter to use (probably a ",")
     * @return the delimited String
     */
    public static String arrayToDelimitedString(Object[] arr, String delim) {
        if (ObjectUtils.isEmpty(arr)) {
            return "";
        }
        if (arr.length == 1) {
            return ObjectUtils.nullSafeToString(arr[0]);
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < arr.length; i++) {
            if (i > 0) {
                sb.append(delim);
            }
            sb.append(arr[i]);
        }
        return sb.toString();
    }

    /**
     * Convenience method to return a String array as a CSV String. E.g. useful
     * for {@code toString()} implementations.
     *
     * @param ex the array to display
     * @return the delimited String
     */
    /*
     * public static String arrayToCommaDelimitedString(Object[] arr) { return
     * arrayToDelimitedString(arr, ","); }
     */
    public static String getStackTrace(Throwable ex) {
        ByteArrayOutputStream buf = new java.io.ByteArrayOutputStream();
        try {
            ex.printStackTrace(new java.io.PrintWriter(buf, true));
            return buf.toString();
        } catch (Exception e) {
            throw e;
        } finally {
            try {
                buf.close();
            } catch (Exception a) {
            }
        }
    }

    public static String trimRight(String source, String opr) {
        if (isEmpty(source) || isEmpty(opr)) {
            return "";
        }
        String leftOpr = source.substring((source.length() - opr.length()), source.length());
        if (opr.equals(leftOpr)) {
            return source.substring(0, (source.length() - opr.length()));
        }
        return source;
    }

    /**
     * 过滤大于四个字节的utf8的字符串
     *
     * @param text
     * @return
     * @throws UnsupportedEncodingException
     */
    public static String filterOffUtf8Mb4(String text) throws UnsupportedEncodingException {
        byte[] bytes = text.getBytes("utf-8");
        ByteBuffer buffer = ByteBuffer.allocate(bytes.length);
        int i = 0;
        while (i < bytes.length) {
            short b = bytes[i];
            if (b > 0) {
                buffer.put(bytes[i++]);
                continue;
            }

            b += 256; // 去掉符号位

            if (((b >> 5) ^ 0x6) == 0) {
                buffer.put(bytes, i, 2);
                i += 2;
            } else if (((b >> 4) ^ 0xE) == 0) {
                buffer.put(bytes, i, 3);
                i += 3;
            } else if (((b >> 3) ^ 0x1E) == 0) {
                i += 4;
            } else if (((b >> 2) ^ 0x3E) == 0) {
                i += 5;
            } else if (((b >> 1) ^ 0x7E) == 0) {
                i += 6;
            } else {
                buffer.put(bytes[i++]);
            }
        }
        buffer.flip();
        return new String(buffer.array(), "utf-8");
    }

    /**
     * safe equals
     *
     * @param cs1
     * @param cs2
     * @return
     */
    public static boolean equals(CharSequence cs1, CharSequence cs2) {
        return cs1 == null ? cs2 == null : cs1.equals(cs2);
    }

    /**
     * @param seq
     * @param searchSeq
     * @return
     */
    public static boolean contains(CharSequence seq, CharSequence searchSeq) {
        return seq != null && searchSeq != null ? indexOf(seq, searchSeq, 0) >= 0 : false;
    }

    public static int indexOf(CharSequence cs, CharSequence searchChar, int start) {
        return cs.toString().indexOf(searchChar.toString(), start);
    }

    /**
     * 过滤html
     */
    public static String delHTMLTag(String htmlStr) {
        String regEx_script = "<script[^>]*?>[\\s\\S]*?<\\/script>"; //定义script的正则表达式
        String regEx_style = "<style[^>]*?>[\\s\\S]*?<\\/style>"; //定义style的正则表达式
        String regEx_html = "<[^>]+>"; //定义HTML标签的正则表达式

        Pattern p_script = Pattern.compile(regEx_script, Pattern.CASE_INSENSITIVE);
        Matcher m_script = p_script.matcher(htmlStr);
        htmlStr = m_script.replaceAll(""); //过滤script标签

        Pattern p_style = Pattern.compile(regEx_style, Pattern.CASE_INSENSITIVE);
        Matcher m_style = p_style.matcher(htmlStr);
        htmlStr = m_style.replaceAll(""); //过滤style标签

        Pattern p_html = Pattern.compile(regEx_html, Pattern.CASE_INSENSITIVE);
        Matcher m_html = p_html.matcher(htmlStr);
        htmlStr = m_html.replaceAll(""); //过滤html标签

        return htmlStr.trim(); //返回文本字符串
    }
}
